Photoshop Tutorial
Osian Haines
August 11, 2008
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Photoshop Tutorial
Contents
Basic Tasks 1
Opening an Image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Saving an Image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Zooming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Undo and History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Other Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Simple Editing 7
Resizing a photo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Cropping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
More Advanced Tools 10
Lightening and Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Colours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Sharpening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Basic Tasks
Opening an Image
There are several ways to open an image to edit in photoshop – like through photoshop, through a
folder or through an image viewer.
Note: When opening images, sometimes a message pops up about the embedded profile being a
mismatch. ALl this means is that the colour settings of the image are a bit different from the default
photoshop settings – as is often the case with digital photos.
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Photoshop Tutorial
This is nothing to worry about and makes no difference, you can safely ignore it by clicking OK. Check
the box if you don’t want to see the warning again.
Opening photoshop first
To open Photoshop, just go to Start > All Programs > Adobe Photoshop CS.
Then, it’s the usual process of File > Open, and choose the file you want.
Photoshop can open images of pretty much any type. Photos are usuall .jpg, but it will also open .gif,
.bmp, .psd etc.
Choose the file you want and click open.
From a folder
When vieweing a folder full of images, you can open one for editing from the right-click menu. Right
click on the icon, and choose Edit With Photoshop.
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Photoshop Tutorial
From Picture Viewer
Usually if you are looking at am image, it will be in WIndow Picture and Fax viewer.
You can open for editing the image you are vieweing straight from here. Right click on the edit-image
button (circled) and choose Edit With Photoshop from the menu.
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Photoshop Tutorial
Saving an Image
Photoshop can save an image in many different images formats. For photos, you would normally want
to save in .jpg. The default format is .psd – this is the photoshop format, which saves layers and other
information – it is useful when making big changes to images that you want to be able to alter later.
For simple images, therefore, change the format from Photoshop to JPEG. Then name you file and
click save (you could keep the same file name and overwrite the original, but better to give it a new
name to keep a backup copy).
Next a dialog box appears to control the quality of the image. This is because JPEG files compress
the image, and you can choose how much compression to apply. The higher the value, the better the
image will appear, but the more space it takes up. The difference will not be very noticeable, except
in fine details. As the quality slider is moved, the size of the image is shown in Kb at the bottom of
the dialog box. Files above 300Kb will take a noticeable time to send or load – but digitial photos
start at around 1000Kb, so this is still an imprvement. It will also give an estimate of how long it
would take to download at different connection speeds – the default, as selected by the dropdown box,
is 56K modem (old dialup), while boradband is at 1Mbps.
As the slider is moved, if the ‘Preview’ box is checked, the image will (temporarily) change to show the
effect of reducing the quality (note that unless you are viewing the image at 100% zoom you might not
see the loss in quality). A quality of 7 is usually a good compromise but it depends on the purpose,
required quality and required file size. The Matte and Format Options are not important.
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Zooming
You can view at image at different levels of zoom – to see the whole thing, to see it actual size, or to
view a small detail, for example. Of course this makes to change to the actual image – just how you
see it (remember that the part of the image you see in the window will not necessarily be the whoile
image).
The quickest way to zoom in and out is to use the scroll whell. Scrolling the wheel down will zoom
in, and up will zoom out. In some situations this will cause the image to scroll up and down instead
of zooming – to make it zoom, hold down the Alt key while moving the wheel. ALso note that, using
the scroll wheel while the mouse is over one the the scrollbars, will scroll the image in that direction).
Use the zoom tool (circled in green) for finer control over the zoom. This causes the cursor to turn
into a magnifying glass (with a plus symbol), so clicking on the image will zoom in on that location.
This can be changed to a zoom-out magnifying glass my selecting the magnifying glass witha minus
sign in it from the toolbar at the top left of the screen. When using the zoom-ion magnifying tool,
you can drag a box over the image, which will zoom in to the image to show whatever is in the box.
Right clicking while using the magnifying tool will bring up a useful menu. The first option is to Fit
On Screen, which will make sure you can see the entire image, no matter what size it is (useful for
looking at a whole photo). The Actual Size option will show the image at 100% zoom, it’s actual size
– this is useful for seeing the finest details the image really has, and seeing what the image will really
look like. It is easier to use this option to get to actual size than to try to get there using the zoom
in and out tools. Also in the menu are zoom in and zoom out, which can be easier to access than
switching the magnifyer to zoom in or zoom out (as above).
At all times, the size the image is being viewed at is shown in the title bar of the image window. Note
that when an image is not at 100%, artefacts and imperfections may be visible, which are not actually
in the image (caused by aliasing). This can mean that if an image is being viewed at 104%, though it
is almost actual size, it could look different from the real version (messy lines, blurriness, etc).
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Undo and History
Photoshop, like almost every other program, has an Undo feature (in the Edit menu, or shortcut
Ctrl+Z). However, this will only undo the last command – choosing to undo again will just undo the
undo, leaving you back where you started.
This initially seems very limiting, but this is what the History pane is for, on the left of the main
window. Listed here are all the recent things done to the image. Clicking on any of the steps listed
will take the image back to one of its past states (and allow you to jump forwards again, so long as
you don’t change anything – a bit like time travel). To revert the image to a previous state, choose
the command up to which you want to undo, and press the ‘Delete Current State’ button (looks like
a bin). Note that this deletes everything back to, and including, the selected state – which means the
image goes back one step further than you currently see. This can be confusing – the best strategy
is to choose the state you want to go back to, then select the NEXT one (one down, into the future)
and click delete.
Note that in photoshop, everything you do goes into the history – including things like selections. This
means if you spent a while selecting exactly the right area of the image for something and then lose
it, you can undo and get it back (this doesn’t always apply, for example when you are ion cropping
mode, where these actions will just get lumped together as a single cropping action).
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Other Notes
Selecting
Use the selection tool (top left in the toolbox) to be able to drag square (or other shape) regions to
select. When something is selected, it can be manipulated on its own – for example enhancing the
contrast on a small part of the image. Advanced options for controlling selections exist, in the Select
menu (like expanding or smoothing the slection area). These are more useful when doing things to
certain parts of photos, but can get tricky.
A useful thing is to be able to clear the selection. Press Ctrl+D and whatever is selected will be
deselected. Ctrl+A will select the entire image.
Drawing/selecting things
Various key combinations can make selecting an area / drawing shapes etc easier. Usually, where the
mouse drag begins is the top left corner of the selection. But if Alt is held while selecting (pressing it
before or after starting to drag), then where the drag starts will be the centre of the region – useful
when you want a box centred on something. Note that you need to release the mouse button before
the Alt key, or the selection will flip back to the normal top-left-first mode.
Another useful key is shift – holding this while selecting will draw a perfectly square (or circular)
region. It can be used in combination with alt to draw circles centred on a specific point, and so on.
Simple Editing
Resizing a photo
Photoshop can be used to make photos smaller, while preserving the aspect ration. Size can be spec-
ified either in pixels, percentage of original size, or as an actual distance measurement.
First, open the image (see ). To simply resize the image, go to Image Size in the Image menu (not
Canvas size, this is different).
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This will open the Image Size dialog box. The top section of this lets you change the pixel dimensions
of the image. Normally the width and height values are linked, so if you change one, the other changes
too, to keep the same aspect ratio (the little chain symbol on the left – green circle). To be able to
change both independently, uncheck the ‘Constrain Proportions’ box. Doing this will elt you squash
and stretch the image.
The pixel size of the image will be quite large, and can be reduced considerably without losing a lot
of detail. The width of the monitor, in pixels, is about 1000. The Document Size box can be used to
choose the size, or to get some idea of how big the image really is, as it can display the size in cm or
inches. These values are tied to the Pixel Size values above – they change together, so use one or the
other.
Alternatively, the size can be changed by percentages – a simply way of making the image half its
original size, for example. This dialog can be used to make the image bigger, but of course there will
be a loss in quality.
Cropping
Photoshop has a simple tool for cropping images, which can be found on the toolbar on the left.
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After selecting the crop tool, drag an area on the image that you want to crop. The area outside
of the crop region will be shaded darker, giving you a preview of what the image will look like after
cropping. The size of the crop region can be altered by miving the little square handles (circled in red)
at the edges and corners of the cropped region. You can also draw the crop boundary from outside
the image, so that it covers all of the image, or all of one side, then adjust the size until it looks right.
Notice how, near the edges of the image, the crop boundary will snap to the edge of the image, as it
assumes if you are nearly at the edge, you will want to go right up to it. This can make it difficult
to make small asjustmens, but the edge snapping can be turned off by holding the Ctrl key as the
boundaries of the crop region are moved.
The entire crop region can be moved over the image by dragging inside (non-shaded) crop region. Be
careful not to drag too near the central marker cross (this can be useful for judging what is in the
middle), as this will just move the cross (which there is no need to do).
To crop the image to the desired size, press enter.
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More Advanced Tools
Lightening and Contrast
Photoshop can be used to make vast improvements to imges, in lighting, colour, contrast, detail, and
so on. The simplest way, which is often very effective, is to change the brightness and contrast. To do
this, go to Image > Adjustments > Brightness/Contrast, which will open the Brightness and COntrast
dialog box.
This has a slider for brightness and contrast, which are both initially centred at 0. Obviously, changing
the brightness slider (or typing a value in the box) will alter the brightness – beware that increasing
it too much can make the image look too white and washed-out. Small increases to the contrast slider
can make the colours stand out better (especially after some brightening), while decrerasing contrast
can make images with too much bright colour look better. Large changes to contrast will usually look
very wrong.
As long as the preview checkbox is ticked, the image will change as the sliders are moved, allowing you
to view your changes immediately. The preview can be turned on and off with this checkbox, which
can be an easy way to compare before-and-after, to check it is actually an improvement. Cancelling the
dialog box will not make any changes. Press OK to permanently alter the image – note that once this
is done, it cannot be easily undone (except using undo) – if yuo go back into the Brightness/Contrast
dialog, the sliders will be back to 0, as the change has been actually applied to the image.
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Colours
The colour balance of an image can be altered using the Colour Balance dialog box – go to Image >
Adjustments >Colour Balance (or use the schortcut Ctrl+B). The kets you increase or decrease the
amount of red, green and blue present in the image. (Normally it works on mid-tones which is fine,
but if you specifically want to change the colours in the lighter or darker regions, choose ‘Shadows’
or ‘Highlights’ at the bottom – ignore ‘Preserve Luminosity’). This box also has a preview checkbox,
which you can turn on and off, and similarly once the change has taken place, the image is altered
and the sldiers will all go back to 0 again next time. As before, small changes are likely to be most
effective on photos (sliders or numbers in boxes), without looking too fake.
For a different way of altering the colour, the hue can be changed – which is a way of changing all
of the colours. Go to Image ¿ Adjustments > Hue/Saturation (or use the shortcut Ctrl+U). This
dialog allows you to change the Hue, which can have dramatic yet interesting effects. Also this lets
you change the lightness, which is basically another way of lightening and darkening the image. The
other slider is saturation – turning this up will make colours more vivid, turning it down will move it
more towards shades of grey. This means you can use it to convert an image to black-and-white (or
just use shortcut Ctrl+Shift+U).
Sharpening
The sharpening and enhancement ability of photoshop are quite powerful. The easiest and most
effective/controllable way is to use Unsharp Mask, from the Filter > Sharpen menu.
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The Unsharp Mask dialog shows a full-size preview segment of the image. Yyou can change where in
the image this shows by clicking in the image (square shaped cursor) – but it may be easier to see what
is going on if the image is viewed at 100% anyway (you can scroll using the scrollbars but not zoom
while the Unsharp Mask dialog box is open). There are three sliders present – the first two control
how strong the sharpening effect is. It works by increasing the contrast in regions of higher contrast
– so it makes edges more pronounced. Applied subtly this can make the image look less blurred, but
overdoing it can make it look fake and too strongly lined. The best results will be obtained by moving
the first two sliders around, while looking at a fairly detailed part of the image at 100% zoom, and
turning the preview on/off to see what difference it makes. Turning the threshold value up will make
it have less effect – this can just be left at 1 in most cases.
Shown here is an image, first the original, then with subtle unsharp-mask applied to improve it, then
with too much.
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